﻿<!DOCTYPE html>
<html>
<head>
    <title>CGI</title>
</head>
<body>
    <h1>Our Page</h1>
    <script>
        //01 variable is not initialize, hence set automatically to undefined

        //var productId;
        console.log(typeof productId);


        //02 empty object
        /*
        var productId = null;
        console.log(typeof productId);
        console.log(typeof null);
        */

        //03  undefined is type of undefined and object is type of null, hence false
        /*
        console.log(undefined == null);
        console.log(undefined === null);
       */
    </script>
</body>
</html>